There is an ever-increasing demand for high-speed or high-bandwidth communication channels for delivering high-speed data and video services. To meet this demand, telecommunications service providers are developing networks (sometimes referred to as outside plant networks) that extend the higher bandwidth of fiber optic components all the way to the end-user businesses and homes (referred to as premises). In such networks, there are distribution points where a distribution, feeder or branch cable is interconnected with one or more drop cables that are routed to the premises. At such distribution points, the side coming from the service provider is generally referred to as the central office or CO side while the side leading to the premises is generally referred to as the drop side. A distribution, branch or feeder cable typically includes a sheath surrounding a plurality of buffer tubes with each buffer tube housing a plurality of optical fibers.
Enclosures are used to house fiber optic cable interconnections and splices and certain fiber optic components (e.g., splitters and couplers) at various locations in a fiber optic network. Existing fiber optic enclosures, however, are not well suited for use at distribution points close to the end-user premises. Technicians will have to access the interior of the enclosures at such distribution points on a fairly regular basis to add new splices for the premises of additional subscribers or to disconnect service to subscribers canceling service. Vault-type enclosures that are buried in the ground are one type of enclosure commonly used in fiber optic networks. Such vaults are thought to be necessary to protect the integrity of the optical fibers and splices. However, to gain access to the splices in the vault, a bulky lid with multiple bolts must be removed and a sealed splice case, also with multiple fasteners and cable sealing provisions, removed from the interior of the vault. As a result, accessing and servicing such vaults is time-consuming, and thus expensive, making them unsuitable for use at distribution points close to premises that will have to be accessed by technicians on a regular basis.
In addition, performing splicing operations in the field can also be very awkward when working with buried vault enclosures. In particular, when the sealed splice case is removed, lengthy slack fiber loops must also be removed from the vault so that the splice case can reach a clean area where the splicing can be performed. Once the splice case is situated in the clean splicing area, actually gaining access to the splices can sometimes involve the removal of over a dozen threaded fasteners. Once the splicing operation is completed, these steps must be repeated in order to replace the splice case back in the vault. Failure to properly reseal the cable openings and tighten the fasteners often results in water leakage into the splice case that may cause undesirable optical signal degradation.
The routing and management of the fiber optic cables in such vaults can also lead to problems. For example, with such vaults, there is a significant risk that a technician will disrupt the unopened buffer tubes (known as “express buffer tubes”) that extend in an uninterrupted manner through the vault in the course of performing the splicing operation. Obviously, this issue is of particular significance when the vault is being used at a distribution point to premises that will have to be accessed frequently for field splicing operations. The cable routing and management in such vaults can also be quite complicated further increasing the potential for errors by technicians performing work on the equipment in the vault. Other types of enclosures used in fiber optic networks have similar issues and drawbacks.
It can be relatively difficult and time consuming to separate the express buffer tubes from the spliced buffer tubes and find the appropriate optical fibers when adding or reconfiguring splices to drop cables in an enclosure. Also difficult and time consuming to access the splice tray to perform the splicing operation without damaging the express buffer tubes. Thus, such field splicing operations frequently require a highly skilled technician. However, highly skilled technicians are expensive.